Automobile of the crawler type



Patented Nov. 1o, 1931 UNITED STATE-s ERNST RNN KORNBECK,

COPENHAGEN, DENMARK AUTOMOBILE. OF THE CRAWLER `TYPE Application iled February 10, 1928, Serial No.

This invention relates to power driven field `vehicles such as field autos wherein a' traction belt envelops a drive wheel and a plurality of rolls which are arranged to form an ex- 5 pending system which acts to expand or tense the belt and increase the friction between the same and said drive wheel when the vehicl-e encounters roughor soft ground.

,It is of course an accepted fact that field automobiles, i. e. automobiles which have to be driven not only along improved roads but also across uneven fields, soft ground and the like, have to fill certain requirements which are to some extent incompatible. Since the 'motion of the automobile in ar country with a well developed net of roads will mainly be along smooth roads, the automobile must be suited for fast'driving on the' road,

Vand it must be able to endure such driving,

and it must be easy and safe to steer, which last conditionrequires a sufficient steeringwheel pressure. Away from improved roads it must also be able safely to pass uneven or soft ground and to move along quite considerably sloping ground.

The ordinary freight automobile meets Well enough the requirements tol be filled when driven alongimproved roads,'but not 'the requirements to be filled during passage over unimproved roads. When soft'ground occurs, the said requirements are best filled by an automobile with driving belts, and Y where the ground is especially uneven,they are best filledby an automobile with two driv- 30 ing axles. t

The present invention has for its object to provide such an arrangementof the driving mechanism of theautomobile that', all the above mentioned different necessary requirements will be filled simultaneously, vwhereby reliable driving of the automobileon uneven ground may be secured simultaneously with fast and safe driving on improved road without any excessive wear on anyof the parts'of the driving. mechanism. According to Vthe invention this object is attained by building the automobile like an ordinary freight automobile, in so far as it .is fitted with front wheels (steering'wheels) o Y as well as with rear wheels (drivingwheels) g ing for instance Von soft ground will be essen- 253,482, and in Denmark February 1e, i927. f

' but is further fitted with a driving belt which passes about the rear wheel and a guiding roll. Saiddriving belt is actuated by'pres sure rolls, and extends towards the front wheel in such a manner that the rear wheelfl Vwhen the supporting rolls enter intooperation, will serve as driving wheel for the belt, and vwill pull towards the rear the bottom part of the said belt, whereby the automobile. itself will be pulled forward. j I 1 According to the invention means are furthervprovided to prevent the saidsupporting rolls from becoming operativer as such, las

long as the automobile is drivenalong im- ,4 proved roads, but to cause'them on the other 35 hand to take care of the load, automatically,

as soon as the rear wheels, during driving .along uneven or soft ground, refuse to operate as supporting members, there being at"` the'same time produced such a belty tension, 70 i increasing with the decreasingactivity lof the rear wheels as supporting 4 members, that there will be generated, between the periph'- ery of the driven rear ,wheels and the surface t of thetwo belts passing each y,about one ofe'75 the rear wheels, `the friction needed for reliable action ofthe drivingfmechanism. 4The belt itself'is'adjusted in such yal manner that it will be practically f free of tension, whenw the automobile is ldriven along improved roads. By the above mentionedcombined arrangement of the driving mechanism the belt, 4when driving along :improved road-s, will only be exposed to compression, viz. be-

low the rear wheel ofthe automobile, and,"

consequently only to slight wear, and asexplained below the further advantage will be attained that although during driving along improved roads the front wheels of theautor mobile are exposed to the relatively high; gf wheel pressure whichl isV necessary for reliable steering ofthe automobileduring fast driving, then this wheel pressure when drivtially reduced since it is partly transmitted tothe system of supporting rolls, or4v idler rolls 5, 5 as they may also betermed.

`The invention is illustrated in one vsingle. I embodiment on the drawings, where y' um Fig. lshows the rearjportionof an auto-rY mobile according to the invention here referred to, and

Fig. 2 is a cross-section along the line II-II in Fig. 1.

On the drawings 1 is the underframe proper which in' ordinary manner is supported by the rear-wheel axle 3 by way of springs 2. The rear wheelsare fitted with suitable felloes 12. Near the rear-wheel axle 3, but not coincident with the latter, Afixed pivots 10 are provided for a'single-armed lever 9 the free end 10 of which is fitted with a shaft for a guiding roll 11. Itshould be noted that there are ofcourse two such levers 9, viz. one on each side of the vehicle, and when in the following one side is described then it will be clear that all these members are provided correspondingly7 on the opposite side of the vehicle. y

The lever 9 may suitably be made in two pieces between which a spring 15 may be inserted in a sleeve, the said spring being compressed when the tension in the belt becomes too high. An endless band or belt 13 passes about the rear-wheel felloe 12 and the guiding roll 11, in such a manner, that the said belt may be given a suitable degree of tightness by means of the spring 15. Transversely to the two levers 9 there is provided a shaft 7 supported by brackets 8 on the levers 9. On the ends of the said shaft 7 there is journalled a bell-crank lever 6 to one extremity of which there is journalled another bell-crank lever, rolls 5 being provided at the ends of all three lever arms which may be fork-shaped so as to straddle the running rolls. Finally one or more springs 4 are inserted between the levers 9 and the underframe 1 of the vehicle.

When the automobile is travelling on improved roads there is very little tension in the belt 13, in fact the principal stress to which the belt is then subject is one of compression between the felloe 12 and the road. Since there is such reduced tension in the belt, rolls 5 being1 on lever 9, will be slightly raised and normally vidling and carried on belt 13 which is notin contact with the road at this point under such conditions.V A manually control-led means 14 integral with axle 7 is attached to Vbut operated adjustably at the underframe or from the drivers seat in such a manner so that when the automobile i-s travelling on an improved road Vthe rolls 5 may' be maintained sothat they do not exertv any pressure on the belt 13. W hen the automobile leaves improved roads however and enters an unimproved road or soft ground, then the Vrear wheels will sinl; into theground andthe rolls 5 will thereby be loaded. It is manifest that the driving wheel, lever 9, pivot 10 above the` rear shaft 3- and the guide roll 11 constitute an expanding system in which two of the pivots, that is shaft 3 and pivot 10 are stationaryA relative to the vehicle itself while actuation of said system through loading of the idler or supporting rolls tends to expand or tense the belt thereby improving the traction of the vehicle over unequal ground surfaces.

The vertical pressure on the rear wheels proper will thus be reduced proportionally to the sinking of the rear wheels, and the load on the rolls 5 will increase correspondingly, and this pressure will be transmitted to the underframe by way of the levers 9 and the springs 4. The compression of the springs 4 will cause the arms 9 to swing somewhat upward whereby owing to the eccentric arrangement of the lever arms 9 relatively to the rear axle `3 a tension will be introduced in the belt 13 which tension will increase with the load onthe rolls and will produce a friction between the belt 13 and the wheel felloe 12, Vinsuch a manner that the pull from the rear wheel will now betransmitted partly by means of the decreasing rear-wheel pressure and partly by the increasing friction between the belt and the felloe.

Having now described my invention, what I claim as new and desire to secure by Letters Patent is:

1. In a held automobile having an endless belt enveloping a rear wheel thereof and arranged to be. driven by said wheel, anex- 4panding system for increasing the friction of said belt with respect to said rear wheel, including the combination, with a shaft for Y said rear wheel, of a lever pivoted at one end a distance above said shaft and arranged with its free end ka distance below the general level of the pivoted end thereof and swingable in a vertical plane, a guiding roll rotatably borne upon the free end of said lever within said belt, idler rolls rotatably borne beneath an intermediate portion of said lever within said belt and normally making light traction therewith, and resilient means associated with said lever between the intermediate portion of the lever and-said guiding roll to relieve excess strain upon said belt during expansion thereof, said lever being swung upward against the resistance of the belt andV tending to expand said belt by increasing the distance between said guiding roll and said drive wheel upon the latter encountering soft or irregular ground surface, which tends to change the level of said idler rolls with respect to the rear wheel and thereby positively raise said lever intoexpanding position..V l

2; In afield automobile having an endless beltl enveloping a rear wheel thereof and arranged to-be driven by said wheel, an expanding system for increasing the yfriction of said belt with respect to said rearwheel, including the combinatiomkwith a shaft for said rear wheel,of a lever pivoted at one end a distance above said shaft and arranged with its free end a distance below the genera-l level of the pivoted end thereof and swingable in a vertical plane, a guiding roll rotatably borne upon the free end of said lever within said belt, idler rolls rotatably borne beneath an intermediate portion of said lever within said belt and normally making light traction therewith, a resilient support also connected to the intermediate portion of said lever and attached t0 said automobile, and resilient means associated with said lever between the intermediate portion of the lever and said guiding roll to relieve excess strain upon said belt during expansion thereof, said lever being swung upward against the resistance of the resilient means and tending to expand said belt by increasing the distance between said guiding roll and said drivewheel'upon the latter encountering soft or irregular ground surface, which tends to change the level of said idler rolls with respect to the rear wheel and thereby positively raise said lever into expanding position. v

3. In a field automobile having an endless belt enveloping a rear wheel thereof and arranged to be driven by said wheel, an expanding system for increasing the friction of said belt with respect to said rear wheel, including the combination, with a shaft for said rear wheel, of a lever pivoted at one end a distance above said shaft and arranged with its free end a distance below the general level of the pivoted end thereof and swingable in a vertical plane, a guiding roll rotatably borne upon the free end of said lever within said belt, idler rolls rotatably borne beneath an intermediate portion of said lever within said belt and normally making light traction therewith, a resilient support also connected to the intermediate portion of said lever and attached to said automobile, an alterable stop arranged to prevent said idler rolls from loading said belt when said automobile is passing over level ground, and resilient means associated with said lever between the intermediate portion of the lever and said guiding roll to relieve excess strain upon said belt during expansion thereof, said lever being swung upward against the resistance of the resilient means and tending to expand said belt by increasing the distance between said guiding roll and said drive wheel upon the latter encountering soft or irregular ground surface, which tends to change the level of said idler rolls with respect to the rear wheel and thereby positively raise said lever into expanding position. 'I

In testimony whereof I affix my signature.

ERNST RQNNE KORNBECK. 

